ML102460559
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).XceIEnergy EC-0441 EC Closeout Package REV.0 Report Date: 10/30/2009 NSP000011
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Caveat Outst EC Number: 0000015044 Revision: 000 Engineering Change EC Number :
0000015044 000 Facility PI Status/Date : CLOSED 10/24/2009 Type/Sub-type :
EVAL /
EC
Title:
EVALUATION OF THE IMPACT OF CONTINUING REFUELING CAVITY LEAKAGE DURING 1R26/2R26 ON CONCLUSIONS OF EC 14139 THAT CONSIDERED THE EFFECTS THROUGH 25 REFUELING OUTAGES. DOMINION ENG. R-4448-00-01 Mod Nbr:
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Units and Systems Facility Unit System System Description PI 0
ZC CONTAINMENT VENT Attributes Attribute Name Value Updated By Last Updated SCRN NO NOT DWNT01 10/11/2009 REQUIRED Notes This evaluation is an extrapolation of a previous evaluation to show the co LI nclusions remain valid. The evaluation does not support a change to any st U ructure, system, component, procedure, design basis, or technical specifica U tion and is not used as a basis for operability. Screening is not required SIMULATOR SYSTEM HEALTH EVAL NO PORC DTE PRIORITY RANKING Topic Notes Topic Notes DESCRIPTION An engineering evaluation EC# 14139 was performed b y Dominion Engineering to assess the potential JUSTIFICATION REVIEWER COMMENTS Cross References XRef Number Sub AR 01160372 AR 01201071 for degradation of containment concrete, reinforcing bar, and containment vessels due to refueling cavity leakage through 25 refueling cycles. Evaluation EC# 15044 assesses the impact of continued leakage through 1 R26 and 2R26 on the conclusions of the original evaluation. The original evaluation was performed in conjunction with RCE01 160372 and was procured safety related under the vendor appendix B program as specified in contract 00026901.
The original evaluation was procured to support RCE01 160372. The new evaluation extrapolates the original results for an additional outage to show the conclusions remain valid. Both the evaluation and the referenced Dominion evaluation are attached in sharepoint under the EC Pkg folder.
Reviewer comments were included within the engineering evaluation. All comments were resolved.
StatusDate Reference Description APPROVED 12/02/2008 Refueling Cavity Leakage Corrective Actions and the LRA APPROVED 10/05/2009 Leakage from Ceiling in Regen HX Room EC 0000014139 CLOSED 05/11/2009 EVALUATION OF EFFECT OF BORATED WATER LEAKS ON
- CONCRETE, REINFORCING BAR Affected Documents Milestone MilestoneDateID Name Req By APPROVED BY 10/13/2009 WTRS02 Myers, Sonja K APPROVED Notes: Tom Downey is qualified to prepare EC-Evaluations. Lora Drenth DLI is qualified to prepare and review EC-evaluations.
U U I concur no 50.59 screening is required.
DLI I approve this EC.
Milestone MilestoneDateID Name Req By CLOSE 10/24/2009 LDWHIP01 Whipple, Linda D CLOSED DSGN VERIFY 10/12/2009 N1 11195 Drenth, Lora D Notes: Comments on form QF-0528 attached to evaluation under ECPkg folder in share LI point.
PREPARED (EVL) 10/11/2009 DWNT01 Downing, Thomas R H/APPR Document References Facilty Doc-Type Sub-Type Doc #
Sheet Rev Minor Rev Date PI EC 0000015044 000 10/24/2009
Adopted suggested language that references the 27 fuel cycle.
Purpose suction has been clarified I. KD Revised evaluation to reference 7 roils as a conservative corrosion rate and added quote from Dominion report that states range of.002 to
.007.
Revised evaluation uses the tomin on evaluation corrosion rate and explains why increased wall loss wH not affect conclusions of the Dominion report. LKD Added paragraph to demonstrate that margin was significant based on the pressure stress < 1/2 the yield strength and the change in margin is < 1%.
Page numbers added to header.
Discussion on available margin and the impact on ASME code design thickness has been explained.
Page numbers have been added.
QF. 0528 (FP.-E-MOD-07) Rev. I XceI Energy Design Review Comment Form Sheet 1 of I
DOCUMENT NUMBER/TITLE: 15044 RLVSION:
(1 DAT 1:
10111100 ITEM REVIEWER'SCOMMENIS PREPAREftS RLVLWLRS
___LESOLUTION_DISPOSIUON In the purpose section, the impression given was that the contact of the borated water with the containment vessel was not to continue beyond refueling outage 1R26. I believe that the actual intent of this evaluation is to evaluate conditions through the 27th cycle of operation (until shutdown for 1R27). Please clarify purpose section.
2 The Dominion evaluation did not consider 5 mils as a conservative corrosion rate. It gave 5 mils as an example of a corrosion rate from a particular test. I suggest that if you choose to use a less conservative corrosion rate than the 7 mils per year assumed in the Dominion evaluation, you will need to more assertively make your point as to why a less conservative corrosion rate remains acceptable. The 7 mils per year assumption was not added as a margin of conservatism, but was a value taken from the Boric Acid Corrosion Guidebook 3
There should be some discussion in the corrosion portion as to how this affects margin management. It should be clear to the reader what type of margin has been lost by a possible 0.19 inch of wall thickness loss.
4 Please page number the evaluation, page x of y, to allow verification that all pages are included.
The evaluation has been reviewed per the requirements of FP-E-EVL-01 Rev. 3 Section 5.3.
No additional comments.
Reviewer:
Date:
I Prepardr: Tom Dwni Date: /o/i3/xc Page 1 of I
QF-0527 (FP-E-MOD-07) Rev. 3 r
XóeI Energy Dest Review Checklist EC Number or Document Number / title / Revision Number [C 5044 I EVALUATION OF THE IMPACT OF CON I1NUINC RE F HO NO CAV1 I Y I AKAG1 DURING 1R26/2R26 ON CONCLUSK)NS OF LC 14139 1 HAT CONSUJIRI Ii WI EFFECTSTHROUGH25REFLJEUNGOUTAGES DOMIN1ON [NO k 44480001 Verifier's Name I Discipline: Lora Drenth / Bonn Acid Corrosion Progiam Owner DESIGN REVIEW CONSlDERATIONS 1.
Were the inputs correctly selected and incorporated into desiqn 2.
Are assumptions necessary to perform the design activity adequately desnbed and reasonable? Where necessary, are the assumptions identified (or subsequent re-verifications when the detailed design activities are completed7 3.
Are the appropriate quality and quality assurance requirements specified?
4.
Are the applicable codes, standards, and regulatory requirements including issue and addends properly identified and are their requirements for design met° 5.
Have applicable construction and operating experience been considered7 6.
Have the design interface requirements been satisfied?
7.
Was an appropriate design method used?
8.
Is the output reasonable compared to inputs?
9.
Are the specified parts, equipment and processes suitable for the required application?
10.
Are the specified materials compatible with each other and the design environmental conditions to which the material will be exposed?
11.
Have adequate maintenance features and requirements been specified?
12.
Are accessibility and other design provisions adequate for performance of needed maintenance and repair?
13.
Has adequate accessibility been provided to perform the in-service inspection expected to be required during the plant life?
14.
Has the design properly considered radiation exposure to the public and plant personnel?
15.
Are the acceptance criteria incorporated in the desi9n documents sufficient to allow verification that design requirements have been satisfactorily accomplished?
16.
Have adequate pre-operational, subsequent periodic test and inspection requirements been appropriately specified, including acceptance criteria?
17.
Are adequate handling, storage, cleaning, and shipping requirements specified?
18.
Are adequate identification requirements specified?
19.
Are requirements for record preparation, review, approval, and retention adequately specified?
20.
Have Design and Operational Margins been considered and documented?
Yr' N
N A L]
L U
[J L
E D E E E COMMENTS: LI None Attached (Use Form QF-0528) LI In EC Topic Notes Form retained in accordance with record retention schedule identified in FP-G-RM-01.
4 Evaluation of Polential Impact ofContmmmcd RtIucling ( a it maIc iii t l2b
- 1. Purpose This evaluation will re ie the
)Let )t the e(w1i Iti 1C( h L through the unit I twct ci c etc 1 opei tion.
hell. c.i w
&l k lfl t.tt 2009 and continue to priiy (} 1 1 I hi e Iu;it i&i hcd ii tic liw' I I 14139, which considered the eitci thuich euk tI titii nd n tt plant operation. The e tlatior k ln pplehIe t unit 2 lIlt 1 )l litul e uItltttn was generic to both units.
- 2. Methodology A.s per EC# 14139 and Dotuinion I'. irieerin l iNtuit R ;
ouMl Rev, ()
- 3. Acceptance Criteria As per EC# 14139 and Duntinion lnicerii ili,tiui R 444 leltI Rev, 0
- 4. Inputs As per EC# 14139 and Dominion Engineering Evaluation R 444 00 01 Rev. 0
- 5. References As per EC# 14139 and Dominion Engineering Evaluation R-4448-00-01 Rev. 0
- 6. Assumptions As per EC# 14139 and Dominion Engineering Evaluation R-4448-00-01 Rev. 0
- 7. Analysis The evaluation performed by Dominion Engineering considered the effects of degradation in four discrete areas: first, a bounding computation of the maximum credible corrosion of the containment lower ellipsoidal shell; second, a computation of the worst case depth of attack of the concrete by dissolution of the cement; third, a check that the effects of carbonation will not have rendered any rebar more susceptible to corrosion; and fourth, a computation of the maximum credible rebar corrosion for bars that are exposed to borated water flowing through cracks in the concrete.
The Dominion Engineering evaluation considered that a conservative corrosion rate to apply for determining the maximum credible wall loss of the containment shell would be 7 mils per year, and when considered to apply over 36 years, would have a resultant 0.25 inch of wall loss. From section 4.2 of the evaluation "Tests at ambient temperature indicate that the rates of corrosion of steel in aerated, concentrated (and in one case saturated) boric acid solutions range between 0.002 to 0.007 inch per year (Section 4.4.1 and page 4-35 of the
Evaluation of Potential Impact of ('ontiiiiied &'1t'lin ( u iI I eakagk' in I Boric Acid Corr hut (
ehooh, lcv, ty. I hc 'c Iat air conservative 1i the eat tent t on since In-iI I 1 -
iioi nhcl n 1 the steel contaitnitent essel \\\\ 1 he nit let ed I a I\\ al 1 in ni it the concrete,"
Dominion 1nWeenhi hen iceded to d&-ftiiiniie a nainili t' conservatism and evuualion of a posaiN1 t).2 nu-h ol \\\\ all lo nit lie iHv function of the conlaintuent. I he C\\ alnat a at one In lcd 1 hit t i ni ol ti would not impact tie safi tiniction of the eonnmnnnenl e'sH, iii In iu\\
that any actual eurrosioti (liseoveted at tie held ouId need tic he ecunpaird to the requirements of the AS MI Sect on \\ ( Ic fdr ieee ituhi lt By extrapohttin the ealuaiioii Ic account lot iii nithlionul net ecie of exposure to the aswued conditions, the Th eai espotne I line is nietcuseil to 37.5 years, and the calculated maJniuni credible aII loss itciedses hinni 11Th inch to 0.26 inch. The onlu jos oh tie eva tuition. \\ Ii mu c&iisi dci H I) 2 inch of wall loss remain valid as the 0,01 inch eliunie is small computed to the nominal 1.5 inch wall thickness and does tiol sin,ni Ficani k chan'e the impact on the safety function of the containment bessel Inch us based nit a comparison ot the 1 1.6ksi pressure stress to tie 34ksi yield stress of the itiaterial. 1-ruin section 4.2 of the Dominion evaluation 'For euniple. nSiflL' a tetmunintie tlnckiiess uI 1.25 inches, the axial tensile stress at the thinned area is given by 'k. 21 (puc 2 iii
[20]) where R is the radius (105 '/2 52.5' 030" ), P is the accident desiun pressure of 46 psig, and t is the remaining thickness, taken u.s I 25 in. I his indicates an axial tensile stress ofH 1,600 psi, which is dr helov the yield stress of 34.0 ksi (Table 1-8 in Chapter (1)1-12 of[21]) at the accident design temperature of 268°F (Sheet 12 in [12]), let alone the tensile strength of about 70 ksi.".
The Dominion evaluation noted that there is significant margin as the 11.6ksi pressure stress is less than half the material yield stress, and less than 20%
of the material minimum tensile strength. As pressure stress is proportional to the shell thickness of 1.5", a change from an assumed thinning from.25 inch to.26 inch would change the available margin by less than 1% and does not change the conclusions of the evaluation. As noted above, any wall loss below the 1.5" design thickness would need to be evaluated in accordance with ASME section IX under the site IWE program for acceptability.
The Dominion Engineering evaluation of the worst case depth of attack on exposed concrete due to dissolution of the cement considered the exposure time to be 25 refueling outage pool-flood periods of 15 days each. The computed depth of attack was 0.31 inches. The correlation is a function oft to the 0.5 power.
Adding an additional 15 day exposure period increases the calculated depth of attack to 0.32 inches. The Dominion evaluation then compared this depth of attack against the various thicknesses of grout or concrete cover used in the design of Prairie Island's containment concrete structures. The conclusion that this loss of concrete section in a wall that varies from 4 to 5 feet thick may be considered insignificant is not affected by the increase of one 1/100th of an inch.
The Dominion Engineering evaluation noted that at one specific point around the fuel transfer tube, the design concrete thickness may be less than a foot, in which
Evaluation of Potential Impact ofCosiiinu&d Rcfucling ( a ih I c;ihar in I R2(i case the loss of0,3 I or 0.32 InclR 1iotild lit
)Cti litallv \\ i1uthd I ;ut h evaluation is subsequently p,loriiied cls\\\\ lute, then he el iiic loan I).
0.32" should be addressed. ()tlici ' ke. neh a cli ire a In' ci-nud insignificant compared to the eotisciv.tlttns uiiiphived in the 'nIaiiiu H the original value, such as the solne\\\\ lint nbitratv douNin H ftc iLin ciniuHat rate proportional constant to account or i teertanit ft'S lii I tic Pt inc specific behavior from eheni sit \\ di eaten in tie cotici tic h The Dominion Itmineerinr e alnation cal Ihe protection aUoided tin ichit by the hydroxides and the loss cal id protect ion due to e;a h unit cii (rear I it ni \\\\ JIlt carbon dioxide in the air oer little), deicrinnied that cat honatuni tiii Iit\\ e penetrated approximately 1.2 inches into the cc)netcte o\\ er the CcJtII5C LO Vn
]This as based on a curve lit and e.ni ipiclation cal' data 'cant NI. RI ( ( 'RH)24 which covered 25 years. Ry icpeaIui the saute e\\ei'eise, using.
\\ cais nisle,id of36 years, we find that the calculated penetration goes trout.1 inch Icc.21 inch, which does not chan c die value to the 1)oniinion Fii'tuecrnig e ahuat ott, which rounded to two siruu fleant henies. titus, the cone hisions ate anal Iceted.
The Dominion Enginceri hg c ahuat ion considered the ecanc stoii H tebar lint is exposed to boric acid leakage through cracks in the concrete. it used a corrosion rate of 0.007 inch per year and art exposure cat 31) da ys per retnehng outage for each of 25 outages, for a total time of 7U days or 2,u yeats. thus the calculated upper limit of rebar corrosion was Ibund to be 0014". l'trapo]atiiig this value to 26 refueling outagec worth of exposure results iii art increase iii corrosion depth from 0.014" to 0.015", The Dominion e atuation judged 0.014" of rebar corrosion to be insignilicant without detailed anal sis. Therelore, 0015" would be similarly insignificant, in light of the supporting data of no visible signs of rebar corrosion such as concrete spalling or rust staining at the leakage locations in containment.
- 8. Conclusions The conclusions reached in the Dominion Engineering evaluation (EC# 14139),
when results are extrapolated for an additional refueling cycle of exposure, remain valid.